Compensated meter



July 14, 1942.

J. L. WHITTEN COMPENSATED METER filed Sept. 1, 1938 INV JAMES L. WHI TENA TTORNEY.

Patented July 14 ,.19 42 Q I UNITED STATE s- P TEN OFFICE COMPENSATEDaren flames L. Whitten, Bucky ltiver, Ohio, assignmto The BrownInstrument Company, Philadelphia, Pa., acorporation of PennsylvaniaApplication September 1', 1938, Serial No. 227,929

a Oialms. (cl, 73-193) The general objectof the present invention is toprovide a continuous measure of the heat content of a flowing stream ofgas, which varies in composition from time to time, in such manner as toeffect related changes in the density and B. t. u. value of the gas. Insome cases, the measurement, effected in accordance with the presentinvention, of the heat content of the tion of 'a fuel gas formed bymixing a low B. t. u.

gas, such as blast furnace or producergas, with is a diagrammaticrepresentation partly in section, ofa preferred embodiment of thepresent invention.

In the drawing, A represents a. conduit-for supplying to a gas burningfurnace (not. shown),

a fuel gas, which is a mixture of a lean gas,

v such as blast furnace gas, supplied to the cpnduit A through a branchsupply conduit AB, and

a rich gas, such as coke oven gas, supplied to the conduit A through abranch supply conduit AC. As shown, the branches AB and AC includethrottling or cut-off valves AB and AC',.respectively, As shown also,the rate at which gas flows through the conduit A is subject to reguasubstantiall'yrichen and lighter, gassuch as v coke oven gas. Under theconditions prevailing in such plants it is frequently impossible fromthe practical standpoint, to avoid substantial lation by a valve AAincluded in the conduit A, and controlled as hereinafter described.

The conduit A includes ameasuring orifice A", and in the drawing, I haveillustrated flow measuring means which is responsive to the differencebetween the pressure at the inlet and outlet sides of the orifice A, andis of the known type, in-

cluding provisions for compensating for variavariations in the B. t. 11.',value of the fuel gas mixture, in particular because it is notpractically feasible lnmany cases, to closely regulate or directlymeasure the relative portions of lean tions in the pressure andtemperature of the j fluid measured, which is disclosed in the Harrisonand rich gas in the mixture, and, volume for: 7 v

. duit A at the highpressure side of a measuring volume, only asmallchange in the mixture ra tie is required for a significant change in theB. t. u. value of the mixture since the heating value of the leangas maywell be only 15 or, 20%

of that of the rich gas.

Under the conditions commonlyprevailing in industrial plants of the kindreferred to, it is practically important to have a measure of the rateat which heating units are supplied to an industrial furnace, toobtain'a correct understanding ofthe furnace operating conditions,

and to permit apparatus and personnel iuefiiciencies to be detected andcorrected.

My present invention isv characterized by the combination with asuitable flow meter for measurlng the rate of gas flow through a furnacefuel supply or other conduit, of means for measuring the density of thegas flowing, and means for combining the two measurements to provide ameasure of the heat content of the gas flow-y ing'through the conduit.In the preferred practical form of carrying out the invention, I makeuse of a known form of flow meter comprising compensating provisions,previouslydevised for' use in measuring a vapor or gas flow, andcorrecting automatically'for variations in the temperature and pressureof the vapor or gas.

The one figure of the accompanying drawing Patent No, 2,052,764, datedSeptember 1, 1936. I Adifferential pressure gauge or manometer B has itshigh pressure leg 13' connected to the con- 'oriflce A therein by apressure transmitting 30 connection b. The low pressure leg B of themanometer B is connected to'the conduit A at the low pressure side ofthe orifice A by a pres- 1 sure transmitting connection b. B designatesa float rising and falling with the changes in level of the manometersealing liquid B, ordinarily mercury, in the low pressure leg 13 of themanometer. The float B is carried by an arm secured to a rock shaft l3projecting through the wall of the manometer and provided externally ofthe latter with an arm 13. The arm B is connected by a link 13'' to themain actuating arm C' of the flow exhibiting and control, or mechanisminstrument D.

The arm 0' is carried by a rock shaft C con-- nected-to, and oscillatingthe instrument shaft E, which carries andgives motion to the flowindicating or recording arm e ofthe instrument. The connections betweenthe shafts C and E comprise an arm c= secured to the shaft c;

and arm E secured to the shaft E, a member F pivotally connected at C tothe arm C, and a link G pivotally connected at E to the arm E of theshaft E, and pivotallyconnected at G' to the member F., Preferably, theaxis of the pivotal connection C coincides with the axis of the pivotalconnection 1? between the arm E and the member G, when-the shaftoccupies its no-flow position, that is, when the float B of themanometer B is in its zero level position. In such condition of theapparatus, the oscillation of the member F about the axis of the pivotalconnection C does not give movement to the arm' E and shaft E. with flowthrough the conduit A, the position of the float, B changes, and theshaft C is turned in the counter-clockwise direction. This moves thepivotal connection C between the arms C and member F countercl0ckwiseabout the axis of the shaft C.

The extent of angular movement imparted to the shaft E, by a givenangular movement of the shaft C, depends upon the displacement of thepivotal connection G' between the members F and G, from the axis of theshaft C. Whenas a result of flow in the conduit A, the arm C isdisplaced in the counter-clockwise direction from the position in whichthe axes of the pivotal connections C and E coincide, any angularmovement then given the member F about the pivot C increases ordecreases the lateral displacement of the pivotal connection G from theshaft 0. This, in effect, increases 'or decreases the leverage throughwhich the shaft C acts on the shaft E, accordingly as said displacementis increased ordecreased. In consequence, counter-clockwise angularadjustment of the member F about the axis of the connection C givesmovement to the arm E of the exhibiting mechanism, and thereby to thepointer or pen arm e, in the'same direction as does an increase in therate of gas flow through the conduit. Conversely, a clockwise angularadjustment of the member F moves the am e in the same direction as doesa decrease in the rate of In the apparatus shown in the drawing, thedisplacement of the pivotal connection G from the axis of the shaft Cmay be controlled by the joint action of two pressure responsiveadjusting devices H and I. -As shown, the device H is a Bourdon tube inthe form of a helix, having one end fixed, and having its otherendconnected to a shaft H axially disposed in the helix. A controllingpressure is transmitted to the stationary end of the Bourdon tube by apressure transmitting pipe h. The helical Bourdon tube of device H is sowound that as the pressure in the conduit It increases or decreases, theresultant flexure of the Bourdon tube rotates the shaft H in a clockwiseor counter-clockwise direction, respectively. The shaft H can-iesan armH on one end which is connected by a link H; to a lever K journalled'ona pin F carried by the member F. At its opposite end the shaft H carriesan arm H connected by a link Q H to an arm H iournalied on .the shaft Eand connected to a pen arm H for exhibiting the value of the pressuretransmitted by the pipe h to the device H. r

The device I is shown as generally similar to the pressure responsivedevice H, comprising parts I', P and 1 corresponding to the parts H, Hand H respectively. The Bourdon tube helix of the element 1 has itsstationary end connected to a pressure transmitting pipe f to athermometer bulb i and containing an expansible fluid. The helix deviceI is so wound that when the pressure in the helix increases due to anincrease in temperature of the fluid, the shaft I turns in the clockwisedirection. The arm P or counterclockwise of the device is connected by alink, P to the lever K at the opposite side of thepivot F from that atwhich the lever K is connected to the the pressure transmitted by thepipe 1' to the de- W vice I.

The construction and operation of the compensated flow meter shown inthe drawing, in so far as it. has been described, is in substantialaccordance with the disclosure of the said Harrison Patent No.2,052,764. As the rate of flow through the conduit A increases anddiminishes, the resultant movements of the float B givescounter-clockwise and clockwise adjustments, respectively, to the arm C,and counterclockwise and clockwise adjustments, respectively, to the penarm e.

The device I compensates for the effect on the measuring apparatus of anincrease or decrease in the difference. between the pressures at theinlet and outlet side of the orifice A, which, without change in theweight rate of gas fiow through the conduit, may result from the changein gas velocity caused by the thermal expansion of the gas.

In accordance with the present invention, means are provided formaintaining a pressure in the pipe 1:. and consequentlyin the Bourdon atube of device H, whichincreases and decreases with the density of thegas flowing through the conduit A. The means provided for the purposecomprises a motor driven blower h driven at constant speed. The outletof the blower is connected to one end of the pipe h which thus transmitsto the device H, the blower delivery pressure. The inlet of the bloweris connected by a pipe h to theconduitA.

As those skilled in the art will understand, with the describedarrangement, and with little or no gas discharged by the blower, thepressure at the blower outlet will increase in a definite measurablerelation with the density of the gas within the blower. To permit thecomposition of the gas within the blower to be the same as that of thegas flowing through the conduit A, provision may be made for a smallcontinuous discharge of gas through the blower outlet. To this end, asshown. the outlet is connected to the conduit A by a pipe it including arestricted orifice h.

The ratio of any angular adjustment of the shaft E and pen arms, to thesimultaneously effected angular adiustme'nt of the shaft C, depends uponthe extent of displacement of the connection G from the shaft C, amovement of the connection G toward or away from the shaft E,respectively decreasing or increasing the ratio. The gas densityincrease or decrease which causes the device It transmitted to thedevice H, means a decrease or increase, respectively, in the number ofB. t. u.s in a cubic foot of gas. In consequence the device H isconstructed and arranged so that the pipe It increases or decreases, theconnection G' is adjusted respectively toward or away from the shaft Cto decrease or increase the deflection of the pen arm e. When thepressure in the pipe h is constant, an increase or decrease in thetemperature of the gas flowing through the conduit A and consequentincrease or decrease in the pressure transmitted through the pipe i tothe device I, will cause the latter to give a clockwise adjustment,respectively, to

the lever K, and to correspondingly move the to increase or decrease thepressure 7 iffurnished by the'deiiective position of the arm e, and themeasurements of the gas temperature and density, W flvely', indicatedbythe deflective feet on the pen arm :de'flection. An increase inonepre'ssure tends to neutralize a decrease in 6 I the other of the twopressures. I

The measurements f, the rate of B; t. u. supply,

positions ofthe arms I" and H", are ordinarily recorded on' a recordchart, but the recording provisions which may be added to the mechanismshown are not illustrated herein, as they 1 form no part of the presentinvention, and may takeany one of various well known forms, and inparticular, may be of'the precise form disclosed in the above mentionedprior patent. or-

- dinarily the static gas pressure will not vary enough to have anysigniflcant'eflect upon the density of the gas fiowing.' Also, in somecases, at least, the gas temperature changes will be too small to haveany significant effect upon I the measurements obtained, and in suchcase,

the device Imay be dispensed with, or disconnected from the member F. Aswill be apparent if the link P be disconnected from the lever K,

and the latter be clamped to the member F es by means ,of the set'screwK, the adjustment of the pivotal connection G toward and away from theshaft C will be wholly due to the action of device H. 1 The ratio orproportion of the movements of the shaft E due to a given change thearms. The extent of movements of the pens 40 H and I" may be similarlyadjusted by adjusting the link connections to the arms H and 1 As thoseskilled in the art will realize, the

apparatus disclosed is well adapted to provide a measure .ofpthe B. t;u. value of a mixture of 5 gases differing in B. t. u. value and densityas do blast furnace gas and coke oven gas. While blast furnace gas andcoke oven gas may each vary somewhat in weight and B. t. u. value, the

normal variation in either respect of either gas is relatively small.Normally, a cubic foot of blast furnace gas weighs about twice as muchas a cubic foot of cokeoven gas, and its combustion can be expected toliberate about 100 B. t. u."s,

while the combustion of a cubic foot of coke oven gas may be expected toliberate about 600 B. t. as The weight of a cubic foot'of the mixturewill increase, and its B. t. u. content will decrease, in linearproportion with the percentage of the mixture formed by the blast fur-00 118,06 gas.

. As previously indicated, in some cases, it may I be desirable tocombine with the measuring apparatus already described, means forautomatically adjusting the valve AA as required for. a 05 gas supply;rate such that the rate at which heating units arelibe'rated by thecombustion of the gas will be approximately constant, notwithstandingvariations in 'gas mixture composition effecting its density and B. t.11. value. The 7 drawing diagrammatically illustrates one arrangementfor the purpose, comprising air controller mechanism adiusted by theturning movements of the shaft E.

The air controller mechanism shown comprises 1- f s,asaLsoa connection Gtowardor away from the shaft 0. i I A simultaneous increaseor decreaseinthe pressures. in the pipes h and i, have an additive eta restrictedorifice Of from a-pipelorother source 0 of air under suitable pressure.The pressure of'the air in the nomle O and in the piping connecting thenozzle to the orifice 0' depends upon the throttling efleet ofa flappervalve P jour nailed on a pivot Q, and shown'as gravitationally biased.for movement into the position in which it engages thenozzle member 0and closes the discharge outlet in the latter. In operation, the angularposition of the dapper P is made dependent on the angular position ofthe shaft E through a lever B journalled on the pivot Q, and provided atone end" with a pin R, engaging the underside of the flapper P. Thelever B is connected by a link R" to an arm E secured to the shaft E, insuch manner, that one decrease in the B. t. u. content of the gas flow-.ing, and a consequent clbckwise angular adjust? ment of the shaft E,'the flapper valve P will move toward the nozzle 0 and thus increase thenozzle pressure. j i

The nozzle pressure is transmitted by the pipe 0 to the pressure chamberAA of the fluid pressure motor valve AA. The latter is biased formovement in the closing direction, and is given an opening adjustment byan increase in the pressure transmitted to it by the pipe 0 On anincrease in the B. t. u..rate of flow through the conduit A, resultingin an increase in the pressure transmitted by the pipe It to the device,

H, the flapper valve P is given a. counterclockwise ing a closingadjustment 'of the 'valveAA. The normal B. t. u. value which theinstrument tendsto maintain may be adjusted by shifting nozzle 0 aboutthe axis of shaft Q in any suitable man- .ner. The nozzle may, ifdesired, be fixed in its adjusted position by clamping screw 0.

While in accordance with the provisions of the statutes, I haveillustrated and described the best form of embodiment of my inventionnow I known to me, it will be apparent to those skilled in the art thatchanges may be made in the form of the apparatus disclosed withoutdeparting from the spirit of my invention as set forth in the appendendclaims and that in some cases certain features of my invention may beused to advantage without a corresponding use of other features.

Having now descri bed my invention, what claim as new and desire tosecure by. Letters Patent,is:

1. In apparatus for measuring the rate at which heating units aresupplied by. a flowing stream of fuel gas comprising a variablepercentage of a gas which is higher in density and of lower B. t. u.value than the remainder ofthe mixture, the combinatioh .of exhibitingmeans, means responsive to the velocity of stream flow, a mechanicaltransmission mechanism through which the last mentioned means tends toactuate saidexhibiting means in accordance with'said velocity, and meansresponsive to the density of the gas in the stream for adjusting saidmechanism to therebymodify the actuation of the exhibiting means by thefirst mentioned responsive means in inverse accordance with variationsin said density. i

of fuel gas comprising a variable percentage of a gas which is higher indensity and of lower Y 3 a bleed noasleO constantly receiving airthrough B. t. u: value than the remainder of the mixture,

the combination of means responsive to the velocmodify the extent ofactuation of the exhibiting means by the first mentioned responsivemeans in inverse accordance with variations in said density.

3. In apparatus for measuring -'the rate at which heating units aresupplied by a flowing stream of fuel gas mixture comprising a variablepercentage of one gas which isdifferent in density and din'erent in B.t. u. value than the remainder of the mixture, the combination of meansresponsive to the volumetric flow of said gas mixture, exhibiting means,mechanical connection means through which the first mentionedmeans'actuates saidexhibiting means, and means responsive to the changein the ratio by volume of the said one gas to-the gas mixture andadapted to actuate said exhibiting means Jointly with said flowmeasuring means, said ratio responsive means including means responsiveto the density of said gas mixture and being adapted to actuate saidexhibiting means on an increase or decrease in said density in adirection opposite to that in which said exhibiting means is actuated bythe first mentioned means on an increase or decrease, respectively, insaid volumetric now.

4. In apparatus comprising an element to be actuated in accordance withthe rate at which the heating units are supplied by a flowing stream ofa fuel gas comprising a variable percentage 01 a gas which is. higher indensity and of lower B. t. u. value than the remainder of the mixture,the combination with said element, 01' means re-.

sponsive to the velocity of stream flow, a mechanical transmissionmechanism through which the last mentioned means tends to actuate saidelement in accordance with said velocity, and.

means responsive to the density of the gas in the stream for adjustingsaid mechanism to thereby modify the actuation of said element by'thefirst mentioned responsive means in inverse accordance with variationsin said density.

JAMESL. WHI'I'I'EN.

